Recently, the number of display (exhibition) advertisements, such as large-scale color photographic prints and ink jet prints, is increasing. The exhibiting methods includes, for example, a method of viewing an image formed on a support by light irradiated from the side of the image (reflection system), and a method of viewing the image by light irradiated from the back side of the image (transmission system). It is known that under particular conditions, such as the interior of a room and outdoors at night, the latter transmission system can provide a more vivid image than the former reflection system. Transmission-type image-forming materials/methods that are used for the aforementioned purpose include a printing system, an ink jet system, and a silver salt system. The printing system has an advantage in mass production. However, in the field of display advertisements that exhibit a variety—but a relatively small quantity—of images, an ink jet system or a silver salt system is preferable to the printing system. The ink jet system is becoming popular because of its convenience. On the other hand, the silver salt color photographic print remains superior in the art of advertising, because the silver salt system provides high image quality performance, owing, for example, to high contrast and rich gradation reproduction, and excellent stability of the image.
On the other hand, owing to the recent advancement of computer technologies, image processing in which image digitized reading, by means of a scanner, and the like, is processed on a computer, has been relatively easy to carry out. As a method to expose a light-sensitive material according to digitized image information, an image-forming method in which scanning exposure is carried out using a light source of high light intensity such as a laser or LED, has been rapidly gaining popularity. Resulting from the recent popularization of laser printers and digital prints, the above-said image-forming method has been common. Accordingly, there has been a continual need for a light-sensitive material having characteristics suitable for laser exposure and digital exposure. As print for a display advertisement, higher image density is requested, because a vivid image must be provided from its purpose of use.
Because the larger a display advertisement scale is, the greater the advertising effect is, a large-sized light-sensitive material is demanded for display advertising. According to the size of a light-sensitive material, a fair-sized exposing machine is also inevitably used. However, there is a size limit because of restriction on the size of the light-sensitive material. Therefore, if a large size exceeding the limit size is needed for display, the current practice is to put together two or more sheets of the light-sensitive material. Further, a high-quality image with higher density is requested for the transmission-type light-sensitive material. However, it has been found that, if two or more sheets of light-sensitive material providing a high quality image with high density as mentioned above, are put together to prepare an advertising medium of large size exceeding the above-mentioned limit size of the light-sensitive material, the continuity of the image at the connecting part is too poor to obtain an impressive advertisement of large size. JP-A-2000-249433 (“JP-A” means unexamined published Japanese patent application) discloses that a vivid image can be provided from making the image density higher, but it says nothing about such a problem as the lack of jointing suitability (change of chromaticness at the jointing part) and resolution of the problem.
In these transmission-type light-sensitive materials, two or more of which are put together for the particular use of a large-sized display advertisement, as mentioned above, the performance of the conventional light-sensitive materials is inadequate to keep high image quality with high density, and also inadequate to lessen the change of chromaticness resulting from plural light-sensitive materials that are put together as mentioned above. Therefore, improvement of the transmission-type light-sensitive material has been desired.
Recently, in the field of silver halide printing material for direct view, such as a silver halide color printing paper and a silver halide color display, in addition to a conventional area (plane) exposure system, a so-called scanning exposure system, in which scanning exposure is performed using lasers such as a semiconductor or gas laser, in accordance with digitized image-information, has been rapidly popularized accompanying the progress of computer technology, the popularization of digital cameras, and the progress of exposure technology. It is known that some of the performances that are not so important in a conventional silver halide photographic light-sensitive material for area exposure are becoming important in the aforementioned silver halide photographic light-sensitive material that is used for scanning exposure in accordance with digitized image-information. For instance, demands for the following performances exist:
To obtain sufficient color density even in a scanning exposure in which the exposure time per pixel (picture element) is extremely shorter than the conventional area exposure, a silver halide photographic light-sensitive material with less high illumination intensity reciprocity law failure, is requested. To reduce color-edge definition loss or unpreferable density fluctuation of images adjacent to and considerably different from each other in density or hue, such as narrow lines (for example, letters) and a geometrical pattern, sharpness of the exposure wavelength in each color must be sufficiently high and balance excellent, and further, sensitivity in the high-density region should be sufficiently high. To prevent so-called “tone-jump,” in which density and color look strangely discontinuous on an image with gradation, gradation should not be extremely hard.
On the other hand, among the silver halide color printing materials for direct view, particularly in the color-display silver halide color photographic light-sensitive material having a coating on a transmission support or a semi-transmission support, it is general that the coating amounts of a silver halide and a coupler are larger than those of a silver halide color printing paper having a coating on a reflection-type support, in order to obtain sufficiently high density in the view through a transmission light. The color-developing time of the color-display silver halide photographic light-sensitive material is generally longer than that for color printing papers so that a sufficient color density can be obtained under the conditions of the large coating amount of a silver halide and a coupler, and increased film thickness resulting from the large coating amount. Also in such color display material, a photosensitive material that provides higher vividness and that is suitable to scanning exposure is demanded, accompanying the recent popularization of the scanning exposure system in accordance with digitized image-information. Recently, in particular, ink jet materials have been used for a color display. This situation further increases the demand for a color-display silver halide photosensitive material providing both higher density and high saturation, so that a display material of a silver salt system can keep its superiority to compete with commercial products of the aforementioned other system. However, the present inventors, having studied keenly, have found that an increase in coating amounts of both silver halide and a coupler, to thereby obtain a color-display silver halide photosensitive material providing both higher density and high saturation, causes the problem that fluctuation of image quality resulting from variation of processing is apt to occur. In other words, it has been found that the above-mentioned method has a defect that, resulting from variation of processing compositions and processing conditions, color murkiness occurs in the high-density region; a change in density of the unexposed portion, such as a white character or letter portion on a colored background, is apt to occur, and loss of letter- or image-edge definition is apt to occur.
Hitherto, a technique of a photosensitive material that provides a color density of 2.5 or more, as a printing material using a transmission support, is disclosed in, for example, JP-A-2000-249433. However, these photosensitive materials are unsatisfactory in the point of letter image-edge definition loss. Further, hitherto, a technique of a photosensitive material that is defined by a point gamma on the maximum color density at the time of calibration, is disclosed in, for example, JP-A-2000-227638. However, these photosensitive materials are also unsatisfactory in the point of letter image-edge definition loss. Further, hitherto, a technique to improve loss of letter image-edge definition by gradation control is also disclosed in, for example, JP-A-2000-352795 and JP-A-2001-324783. However, these two publications do not discuss transmission-type photosensitive material and the high-density region that is needed by the above-said photosensitive materials, and the photosensitive materials disclosed in these two publications are unsatisfactory against variation of processing compositions, processing conditions, and the like.
Accordingly, in the field of a color display material for scanning exposure, there is demand for a silver halide photographic light-sensitive material by which both high density and high saturation are obtained stably, even in variation of processing solution compositions and processing conditions, and loss of letter- and image-edge definition is reduced, and also the density of an unexposed portion is stable.
As means for showing many and unspecified persons various images, display methods that use self-emitting images so readily attract public attention that they are prominent (powerful) as an advertising media, in particular. These methods are classified into a method of displaying dynamic picture images by means of electronic display devices, represented by a cathode-ray tube and a plasma display panel, and a method of displaying stationary images by a combination of a transmission-type image-forming material and a light source (a so-called light box). The latter, economically practicable in comparison, is spreading widely. As the transmission-type image-forming method used for the afore-mentioned purpose, there are, for example, a printing system, an ink jet system, and a silver salt system. The printing system is characterized in that it has advantages in mass production and display of the same image. However, in the field of display advertising that produces a variety—but a relatively small quantity—of images, an ink jet system and a silver salt system, which can effectively produce a variety of images, are preferable to the printing system.
Comparing the ink jet system with the silver salt system, they have differing characteristics, as described below. The ink jet system can form images conveniently by means of a relatively economical apparatus. However, this system still leaves unsatisfactory results in image quality, such as contrast. On the other hand, the silver salt system, despite requiring a relatively expensive apparatus and relatively much time and labor for image formation, can provide images of high quality owing to high contrast and rich gradation reproduction. Accordingly, the silver salt system, characterized by end-products with high image quality, is in great demand in the field of advertising media, as a main field.
Further, the images displayed in such media are often formed by superimposing characters or symbols on natural images, such as landscape and figures, and by computer graphics. Recently, even the work of superimposing characters on natural images, as mentioned above, is mostly processed on a computer. Therefore, the image-forming material to be used in the above purpose must display images outputted from a computer.
A scan-exposing apparatus is used to output a computer-outputted image onto a light-sensitive material of the silver salt system. This is an apparatus for recording images, by scan-exposing a light-sensitive material with beams, such as a laser or LED, as a light source, in combination with a polygon mirror, an optical fiber, or the like according to image information. In the scanning exposure system, the exposure time is substantially about 10−4 sec per pixel, to shorten the exposing time required for the entire image, from the viewpoint of enhancing operating efficiency. Therefore, the scan-exposure time is extremely shorter than the exposure time ( 1/10 to 10 sec) of a conventional exposing apparatus.
Printing materials for scanning exposure that can be used for such short exposure have been sold commercially. However, these materials are not yet satisfactory in the point of forming images with high quality resulting from high contrast and rich gradation reproduction—the primary characteristic of the silver salt system. Particularly, this tendency is remarkable in the transmission-type printing material having a transparent or semitransparent support, in which high contrast has an effect on image quality.
Further, some scan-exposure apparatuses have such functions as that users can set a target density, and the apparatus can determine exposure conditions according to the target density set by the users. Such determination of exposure conditions is hereinafter referred to as calibration. If a conventional light-sensitive material is subjected to an exposure process setting at high density by means of the above-mentioned apparatus, color development does not exceed a limited level of density, or, even though colors develop, loss of color definition to another color different from the original color occurs, primarily in the character image, so that the resultant image becomes useless.